Microwave ovens of the type disclosed in U.S. Pat. No. 5,310,978 entitled "METHOD AND APPARATUS FOR CONTROLLING THE TEMPERATURE AND SURFACE TEXTURE OF A FOOD PRODUCT" and jet impingement ovens of the type disclosed in U.S. Pat. No. 5,205,274 entitled "TURNTABLE CONVECTION OVEN" and U.S. Pat. No. 5,131,841 entitled "BALANCED AIR RETURN CONVECTION OVEN" generally operate on the principle that a food product is moved on a conveyor or turntable relative to stationary jets, in the case of the two latter mentioned patents, or an air duct is moved relative to the food product in the first mentioned patent for causing discrete jets of air to sweep across the surface of a food product. Impingement ovens are widely used in commercial food service and food processing applications because the heat transfer rate between the circulating air and food products is significantly greater than that achieved by convection ovens in which diffused air is circulated through a cooking compartment.
The use of jet impingement heating in combination with microwave heating, as generally disclosed in U.S. Pat. No. 5,147,994, offers very rapid heating because microwave energy is used for thawing or heating the food product while intense jets rapidly transfer heat to the surface of the food product. Food products cooked in the combination microwave and jet impingement oven has improved surface texture and is more palatable than food products cooked in a conventional microwave oven.
Difficulty has been encountered heretofore in developing a small oven suitable for home use which incorporates the advantageous features of the combination microwave and jet impingement heating in a unit which is suitable for installation in residential kitchens. Impingement ovens require a relatively high volume of air flow. Large motors and fans generate more noise and consume more electrical power than is desirable in a residential kitchen.
An oven suitable for "built-in" application in residential kitchens is preferably about the same size as conventional "built-in" ovens and installed in a cabinet accessible through an opening formed in a wall. Impingement oven designs heretofore devised have been larger than conventional ovens because of the mechanisms for imparting relative movement between the food product and the impingement jets and the large impingement air circulating systems.